With respect to the current large intelligence monitoring system, how to acquire monitoring information of all the cameras associated with an object in a monitoring network including a plurality of cameras is an issue attracting much attention. For example, in the case that a thief enters a room in a building with a monitoring system, the administrator generally desires to obtain all the history images of the thief captured by the monitoring cameras in the whole building. In some monitoring system this is generally done manually, which exhausts large amount of time and human power.
A method has been suggested in which the images of the same object captured by different cameras are matched based on color and texture features. In the method, the similarity between the images of the same object is calculated depending upon the accurately obtained color features. This method is effective in the case that in all the different cameras the object appears in the front viewing direction. Related document includes M. Farenze et al, “Person Re-identification by Symmetry-Driven Accumulation of Local Features” (IEEE Conference on Computer Vision and Pattern Recognition (CVPR), 2010) (referred to as related document 1).